Tunnel furnace for heat treating objects



June 24, 1958 F. v. F. HERMANS 2,

TUNNEL FURNACE FOR HEAT TREATING OBJECTS Filed March 27, 1956 5 Sheets-Sheet 1 FIGQ1.

III

INVENTOR. F MF. HEPM/P/VJ 'June 24,1958 F. v. F. HER ANS 2,840,361

TUNNEL FURNACE FOR HEAT TREATING OBJECTS Filed March 27, 1956 5 Sheets-Sheet 2 June 24, 1958 I F. v. F. HERMANS 2,340,361

TUNNEL FURNACEFOR HEAT TREATING OBJECTS Filed March 27, 1956 5 Sheets-Sheet 3 5 Sheets-Sheet 4 F. V. F. HERMANS TUNNEL FURNACE FOR VHEAT TREATING OBJECTS a m Ln I June 24; 1958 Filed March 27, 1956 FIG. 16.

V M Lm FIG. 7.

v INVENTOR.

June 24, 1958 F. v. F. HERMYANS 2,340,361

TUNNEL FURNACE FOR 1m TREATING OBJECTS Filed March 27, 1956 5 Sheets-Sheet 5 IN VEN TOR.

TUNNEL FURNACE FOR HEAT TREATING OBJECTS V Fernand Victor Francois Hermans, Uccle, Belgium Application March 27, 1956, Serial No. 574,289

Claims priority, application Belgium April 1, 1955 5 Claims. 01. 263-8) The present invention relates to a tunnel furnace for the heat treatment of objects carried by a permeable conveyor, which causes them to advance in a forced gas current, wherein the heating of different zones successively. traversed by the objects to be treated is effected by forced currents alternately directed from bottom to top and from top to bottom and forming, two by two, eddies having their axis perpendicular to the median vertical plane of the tunnel, neighbouring eddies belonging to two adjacent zones having the same directions of rotation,

Furnaces of this type are used, for example, for the annealing of glass objects or for forming decorations on such objects. p v p It is known that the abovernentioned eddies have the effect of heating more rapidly and-more uniformly the products circulating in a tunnel furnace in the opposite direction to a general current of gases, because of the increase in the speed of circulation of the heating gas in contact with the objects andof the possibility of regulating the temperature of the gas of each eddy, in order to obtain in the tunnel the temperature curve considered the most suitable for the treatment of the objects.

To this end it has been proposed to equip each zone which has to be at a different temperature from that of the adjacent zones, with heating units, for example electric resistances, and to circulate the heating gas in con tact with the objects to be treated with the aid of fans having a vertical axis and disposed in recesses provided in the ceiling and in the floor of the tunnel. L

The present invention has as object a simpler means of creating eddies of heating gas of this type, in cases in which the heating of the zones is effected directly by combustion gases.

According to the invention, the burners corresponding to the heating of one and the same zone are provided with a combustion chamber having a reduced outlet section, so that the burned gases leave the same at high speed parallel to the neighbouring wall of the tunnel and drive the gaseous atmosphere surrounding them inan eddy in the desired direction. j

In other words, in order to efieetthe formation of the desired eddies, use is made of the kinetic energy of the combustion gases of gas burners, or of burners using any other fuel which does not produce products harmful to the objects to be heated. The development of the combustion in a combustion chamber gives rise. to the formation of a relatively great volume of very hot gases which, when leaving at high speed through a relatively small outlet section, are capable of entraining the surrounding atmosphere. This entraining is much more considerable in extent than that obtained when, in tunnel;

furnaces in which heating by direct'fire is applied, use is made of gas burners which discharge directly into the tunnel or below a screen intended principally to avoid the heating of the objects by direct radiation from the flame, and subsidiarily'to render uniform'the supply of heat.

According to one particular embodiment of the invention, the burners of each zone discharge into a' common.

United State a r Patented June '24, 1958.

combustion chamber extending in the direction of the width of the'tunnel and having an outlet slit. 7

According to another advantageous feature nozzles serving toblow hot air into the atmosphere set in motion bywthe ,gases of combustion are disposed-in thecircuit of each eddy. i V The burners of the furnace according to the invention may be detachably mounted across the floor of the furnace, in a similar manner to that proposed'for the inspection of the burners mounted in the side walls of furnaces, and delivering the jets of gas issuing therefrom ina plane perpendicular to the longitudinal axis of the furnace, provided that all the brickwork is carried by a frame- 7 r. I I The mounting of the furnace on a frame permitting thewithdrawal of the burners through the bottom of the floor is relatively far more expensive than the construction of the furnace practically atground level, directly on the ground or on a foundation block. In fact, in order to facilitate the use of the furnace, it is necessary tojbuildthe same slightly above the ground, so that mounting on the above mentioned frame necessitates the hollowing-out of pits giving access to the burners.

If, in these circumstances, construction on a frame is, prohibitive, it is therefore necessary to allow the fura nace to cool in order to beable to inspect the burners,

a mounted in a brickwork block which forms part of the floor andof the bottom part of one of the side walls, and which isremovable laterally so that it can be taken out of the furnace, and in that the duct bringing the fuel gas to the. burners of each row, and also the conductors supplying the electric current for ignition, are detachably connected respectively'to the sources of gas and of cur- .With a furnace of this type, if a burner has to be inspected, it is sufiicient to withdraw, after the style of a drawer, the removable block corresponding to the row of which it forms part, and to close by means of a plate the opening thus formed in the bottom p'art of one of the side walls. This operation must of course be preceded by the disconnection of'the gas duct and of the electric conductors corresponding thereto. The furnace can continue to operate during the inspection, because the disturbance caused by the removal of one transverse row of burners is'not very great.

The lateral displacement of each removable bloc of brickwork is facilitated by a metal frame solid therewith and supporting it.

In practice; each burner is surrounded by a column of refractory material Where it crosses the floor. In one advantageous embodiment, each block of brickwork is wider than these columns of refractory material, and'is solid with a U.-section on which it rests completely and between the flanges of which the gas supply duct'and the current supply conductors appertaining to the burners of V the blockin question are disposed.

Further features and details of the invention will appear in the course of the description of the accompanying drawings, which represent diagrammatically and solely by way'of example, some forms of construction of the tunnel furnace of the invention. 7

Figure Us a view ir'rs'ection through a vertical median plane designated by the line 1 -1 in Fi ures, of the end bustion gases.

of a tunnel furnaceby which the objects to be heated pass into said furnace.

Figure 2 is an elevation oi a part of this furnace where the objects cooh'and of the erid through which they leave.

Figure 3 is a cross section through a plane designated'by theline, III III in Figure 1. i 4 V Figure .4 is a cross-section similar to that in Figure 3, in a modification of the tunnelfurnace according tothe invention, said section being made through a planedesignated by the line IV..IV in Figure 5.

Figure 5 is a longitudinal section through a plane designated by the line VV in Figure 4. g

Figure 6 is a plan viewin horizontal section along the broken line VI-'VI in Figure 7, in a part of another modification of the furnace according to theinvention.

Figure 7 is a cross-se tion along the line VII /II in.

Figures 6 and 8.

Figure 8 is a vertical longitudinal section along the line VIII-VIII i'n'Figures 6.and 7." g,

Figure 9 is a longitudinal section on a larger scale through a burner on the line IXIX in Figure 6.

In these various figures, like elements have been given like references. v

The tunnel furnace shown in Figures 1 to 3 is himnace which serves for the progressive heating of objects, for example glass objects such as bottles, whichare carried by a permeable conveyor 2, which feedsthem in the direction of the arrow X in said furnace in the opposite direction toa current of gas delivered by a fan3. The furnace contains a certain number of Zones whichare successively, traversed ,by the objects to be heated. Three of these zones, extending respectively over the lengthsa, b,

and e, have been shown inFigure 1. In each of' these zones, heating of the objects is efiected by forced currents directed alternately from-bottom totop andfrom top to bottom. These currents form, two by two, eddies which are shown diagrammatically byarrow's', not bearing references." The axes of said eddies are perpendicular to the. median vertical plane of the tunnel, which coincides with the plane of the paper in Figure l. Neighbouring eddies "belonging to two adjacentzones have the same directions of rotation, as will be readily seen by'examination of the arrows'in Figure 1'. V b

The heating of each zone is effected by means of com- The latter are formed at the 'butlet of the burners 5 disposed atthe ends of a common combustion chamber 6 extending in the direction of the. width of the tunnel. Each combustion chamber 6, has an. outlet slit 7 of greatly reduced section in-relation to that of, the

chamber, so that the burned gases issue therefromat high speed. Saidslit 7 is disposed in such manner that the burned gases issuing therefrom at high speed are directed approximately parallel to the fioor 8( In consequence of their greatspeed, they entrain the gaseous atmosphere surroundingthem inan eddy in the desired direction.

In order totacilitate this entraining, a screen 9 is disposed approximately parallelto the direction ofdischarge of. thexburncd gases outside each combustion chamber 6.

Said screen extends from a point behindthis outlet to a,

pointin front of it. b

The formation of the. eddy is also promoted by the presence of a deflecting wall 10 in front of the .outlet orifice of each combustion chamber 6, said deflecting wall being disposed so as progressively to deflect the gaseous current entrained by the combustion gases.

In order further to assist the formation of eddies,

nozzles 11 are provided in ducts 12 connected to arnain.

the burners at the outlet of whichform the combustion V 4 gases intended to cause the formation of an eddy in a determined zone, are individually provided with a com bustion chamber. The different combustion chambers corresponding to one and the same zone have their outlet orifice of reduced section so as to direct the jets of burned gas issuing therefrom at high speed in a full gaseous stream, parallel to the adjacent wall constituted by the floor 8. In Figure 5, the burners are designated by 5 and the combustion chambers by 6', while the outlets of circular section of these combustion chambers are designated by 7.

In the furnace shown in Figures 6 to 9, the burners of each transverse row are surrounded by columnsof refractory material 16 which cross the blocks of brickwork 17 forming part of the floor 8 and of the lower part of one of the side Walls. Each block of brickwork of this kind is laterally removable so as to be adapted to be re moved from the furnace after the style of a drawer in the direction off'the arrow Y in Figure 7.

. The combustible gas mixed with air is supplied to the burners 5 of one and the same row by a pipe 18 which is detachably connected at 19 to a main 20. Each branch 21 of the latter is provided With a stop valve 22 and is equipped with a valve the degree of opening of which is controlled automatically by a thermostat 23 influenced by the temperature in the corresponding zone of the furnace. Each burneris equipped with an ignition device to which current is supplied by conductors such as 24, which are also connected detachably at 26 to fixed conductors 27.

Each block of brickwork 17 rests on a metallic frame 25 with which it is solid and which is thus laterally 'rnovable. Said frame is advantageously constituted by a rolled U-section the flanges of which are directed downwardly, as shown in Figures 8 and 9. Each block of brickwork 17 is wider than the refractory columns 16 and rests completely on the corresponding U-section 25. The latter now has a width such that the gas pipe 18 and the electric conductors 24 appertaining to the burners mounted in the block in question can be easily housed between the flanges of the said U-section.

As will be readily seen, the invention is applicable irrespective of the lawof distribution of the heat desired in the direction of the length of the furnace. In other Words, the temperature may rise or fall or remain constant in any series of sections and the temperature variations may-be effected progressively or abruptly. case of, cooling, the combustion gases may if necessary be made to act as a driving agent for the cold air originating from the outside of the furnace. According to the kind of thermal variation required, the eddies may all have the same direction of rotation, or some may have a direction of rotation. opposed to that of the cddies'in other zones. i

The invention is naturally not limited solely to the forms of construction shown, and modifications may be made to the form, arrangement and construction of certain of the elements used in putting it into effect, without thereby departing from the scope of the invention, provided that said modifications are not in. contradiction to the subject of each of the'claims.

What I claim is: i

' 1. A tunnel furnacefor heat trcating objects having a floor, side walls and afroof, a permeable conveyor in position spaced away, fromv the floor adapted to carry said objects'from one end to the other of thetunnel through different temperature zones, means for forcing a general gas current above said objects from one endto the other, transverse rows of spaced burners disposed under the part of the conveyor carrying the objects to be treated, a combustion chamber .for each burner at the exit of the latter,said combustionchambers'having each an outlet with a cross section reduced relatively to their own cross section, said outlet sections being spaced from the floor and so'disposed that the high speed jets of In the combustion gases issuing therefrom are directed in the direction opposite to that of the general gas current, and a transverse deflecting wall in front of each transverse row of combustion chambers for deflecting the induced current upwards through the permeable conveyor.

2. A tunnel furnace for heat treating objects having a floor, side walls and a roof, a permeable conveyor in position spaced away from the floor adapted to carry said objects from one end to the other of the tunnel through different temperature zones, means for forcing a general gas current above said objects from one end to the other, transverse rows of spaced burners disposed under the part of the conveyor carrying the objects to be treated, a combustion chamber for each burner at the exit of the latter, said combustion chambers having each an outlet with a cross section reduced relatively to their own cross section, said outlet sections being spaced from the floor and so disposed that the high speed jets of combustion gases issuing therefrom are directed in .the

direction opposite to that of the general gas current, an-

individual block of brickwork for each transverse row of burners and corresponding combustion chambers in which said burners and chambers are mounted, each of said blocks forming part of the floor and of the lower part of one of the side walls of the tunnel and being laterally removable, a pipe supplying the burners .of each row with combustible, conductors supplying electric ignition current to the burners of each row, means for detachably connecting respectively to sources of combustible and of current, the pipes and the conductors belonging to the same row of burners, and a transverse deflecting wall in front of each transverse row of combustion chambers for deflecting the induced current upwards through the permeable conveyor.

3. A tunnel furnace for heat treating objects having a floor, side walls and a roof, a permeable conveyor in position spaced away from the floor adapted to carry said objects from one end to the other of the tunnel through diflerent temperature zones, means for forcing a general gas current above said objects from one end to the other, transverse rows of spaced burners disposed under the part of the conveyor carrying the objects to be treated, a combustion chamber for each burner at the exit of the latter, said combustion chambers having each an outlet with a cross section reduced relatively to their own cross section, said outlet sections being spaced from the floor and so disposed that the high speed jets of combustion gases issuing therefrom are directed in the direction opposite to that of the general gas current, an individual block of brickwork for each transverse row of burners and corresponding combustion chambers in which said burners and chambers are mounted, each of said blocks forming part of the floor and of the lower part of one of the side walls of the tunnel and being laterally removable, a metallic frame'for supporting each block of brickwork, each metallic frame being laterally movable with the latter, a pipe supplying the burners of each row with combustible, conductors supplying electric ignition current to the burners of each row, means for detachably connecting respectively to sources of combustible and of current, the pipes and the conductors belonging to the same row of burners, and a transverse deflecting wall in frontof each transverse row of combustion chambers for deflecting the induced current upwards through the permeable conveyor.

4. A tunnel furnace for heat treating objects having a floor, side walls and a roof, a permeable conveyor in position spaced away from the floor adapted to carry said objects from one end to the other of the tunnel through diflerent temperature zones, means for forming a 6 general gas current above said objects from one end to the other, transverse rows of spaced burners disposed under the part of the conveyor carrying the objects to be treated, a combustion chamber for each burnerat the exit of the latter, said combustion chambers having each an outlet with a cross section reduced relatively to their own cross section, said outlet sections being spaced from the floor and so disposed that the high speed jets of combustion gases issuing therefrom are directed in the direction opposite to that of the general gas current, an individual block of brickwork for each transverse row of burners and corresponding combustion chambers in which said burners and chambers are mounted, each of said blocks forming part of the floor and of the lower part of one of the side walls of the tunnel and being laterally removable, a U-section disposed with its flanges downwardly for supporting each block of brickwork, each metallic U-section being laterally movable with the latter, a pipe supplying the burners of each row with combustible, conductors supplying electric ignition current to the burners of each row, means for detachably connecting respectively to sources of combustible and of current, the pipes and the conductors belonging to the same row of burners, and a transverse deflecting wall in front of each transverse row of combustion chambers for deflecting the induced current upwards through the permeable conveyor.

5. A tunnel furnace for heat treating objects having a floor, side walls and a roof, a permeable conveyor in position spaced away from the floor adapted to carry said objects from one end to the other of the tunnel through different temperature zones, means for forcing a general gas current above said objects from one end to the other, transverse rows of spaced burners disposed under the part of the conveyor carrying the objects to be treated, a combustion chamber for each burner at the exit of the latter, said combustion chambers having each an outlet with a cross section reduced relatively to their own cross section, said outlet sections being spaced from the floor and so disposed that the high speed jets of combustion gases issuing therefrom are directed in the direction opposite to that of the general gas current, a column of refractory material surrounding each burner in its passage through the floor, an individual block of brickwork for each transverse row of burnersand in which the columns of refractory material surrounding the corresponding burners are disposed, each of said block of brickwork being wider than the said refractory columns, forming part of the floor and of thelower part of one of the side walls and being laterally removable, a U-section disposed with its flanges downwardly for supporting each block of brickwork, each metallic U-section being laterally movable with the latter, a pipe supplying the burners of each row with combustible disposed between the flanges of said U-section, conductors supplying electric ignition current to the burners of each row disposed between the flanges of said U-section, meansfor detachably connecting respectively to sources of combustible and of current, the pipes and the conductors belonging to the same row of burners, and a transverse deflecting wall in front of each transverse row of combustion chambers for deflecting the induced current upwards through the permeable co'nveyor.

References Cited in the file of this patent UNITED STATES PATENTS Rauen Jan. '16, 1945 

